TABLE 4.
Cross-reactivity of the CTL response for the H3N2 and H3N8 virusesa
| Immunizing virus | In vitro restimulation | % Specific 51Cr releaseb
|
Reciprocal CTLp frequencyc
|
|||
|---|---|---|---|---|---|---|
| Nil | H3N2 | H3N8 | H3N2 | H3N8 | ||
| H3N2 | H3N2 | 1 | 58 | 59 | 1,722 | 1,615 |
| H3N8 | 16 | 50 | 53 | 2,684 | 2,091 | |
| H3N8 | H3N2 | 7 | 63 | 56 | 2,013 | 2,065 |
| H3N8 | 4 | 49 | 45 | 3,914 | 2,781 | |
a
Ig−/− μMT mice were uninfected (Nil) or infected i.n. with 106.8 EID50 of the H3N2 virus or i.p. with 105.2 EID50 of the H3N8 virus and rested for 4 weeks prior to harvesting of CLN, MLN, and spleen cells for bulk culture or LDA assays.
b
Cells were restimulated in vitro with either H3N2- or H3N8-infected stimulators as indicated; values for bulk cultures are shown at an effector-to-target ratio of 25:1 in a 6-h assay using MC57G target cells.
c
LDA cultures were assayed for levels of specific 51Cr release >3 times the standard deviation to calculate reciprocal precursor CTL (CTLp) frequencies (21).